You Do Need power plug adapter while traveling from Mozambique to Swaziland.

Here is Why You Need An Adapter

The outlet and plug type used in Swaziland is M and in Mozambique are C, F and M. This is how they look like.

Mozambique

In Mozambique, outlets of type C, F and M are in use.

Type C

Type F

Type M

Swaziland

In Swaziland, outlets of type M are in use.

Type M